Siblings!
by BronwynBrian
Summary: A James/Lily AU. Lily is Sirius' sister, and he's been telling the other Marauders about her for the year that they've known each other. What happens when they finally meet her, and does James keep his head? DISCLAIMER: NOT JKR, DIDN'T MAKE WRITEY BOOKS, DIDN'T TURN SAID WRITEY BOOKS INTO FILMS. SO THERE
1. Prologue

_**Prologue**_

**_SIRIUS' POV_**

_Sirius' first day at Hogwarts. Sorting is over, and everyone is in their respective common rooms/dorms. Sirius is unpacking his things, but keeping a wary eye on his new room mates. After a while, the tallest of the three walks over to him._

"Hi, mate," He said, running his hand through his already-tussled hair. My eyes flickered quickly between his face and his hands, and he backed up a bit, giving me some space. I inwardly relaxed, but tried to make sure that he didn't notice it. One of the boys in the corner did, I could tell, but I ignored him, and focused on the boy in front of me instead.

"Hello," I responded evenly. He grinned at me.

"So, what's your name?" He asked quickly. I smiled grimly.

"Sirius Black. What's yours?" I smirked when he looked at me sharply, but tried to make sure it wasn't too obvious.

"James Potter. These two-" He gestured to the other boys in the room, who were still standing where he left them. "-are Peter Pettigrew-" The boy on the left waved slightly at me, so I nodded. "-and Remus Lupin." The other boy nodded at me and smiled slightly, and I felt myself begin to blush. Out of all of the boys, he was obviously the sharpest. I definitely needed to keep an eye on him.

While I had been eyeing Remus Lupin, James had continued speaking. "Y'know, I think we're going to be awesome friends. But to become awesome friends, we need to know each other a bit better. Who's up for a game of "truth or dare"?" I glanced up at him and grinned.

"I'm down. What about you guys?" I aimed the last bit towards Remus and Peter, who still hadn't moved. They looked at each other, but both nodded. James and I grinned at each other, and promptly sat down on the floor. The others joined us, forming a circle. "So, who wants to start?"

* * *

><p>Two hours later, we all knew almost everything about each other. For example, James was an only child, his parents were <em>old<em>, he loved Quidditch, and he was aiming to become a professional Quidditch player when he was older. Remus was also an only child, his father had died many years ago (we didn't know how, but none of us were stupid enough to keep pressing), he had all of the books that were needed for the year ahead (and some that we didn't) already, and he wasn't sure what he wanted to be when he was older. Peter was an only child as well (when we'd found this out, I burst out laughing. They all looked at me strangely, so I said "Am I the only one who has a sibling here?" to which they all nodded, laughing along with me.), his mum was a nurse, his dad was a gambler and barely ever home, and he wasn't sure what he wanted to be either.

I had made sure that I hadn't told them anything I didn't want to know about me, so, in the end, I had told them that I had a younger sister called Lily, who would rip your dick off if you looked at her funny, my dad wasn't around anymore, and my mum stayed in her office all day, working on some piece of work or another. I also told them that I wasn't sure what I wanted to be, but I was currently thinking either Auror or professional Quidditch player, like James. James and I had shared a grin when I told them this, and I knew that we were going to be best friends.

"Hey, do any of you know pranks?" James asked suddenly. My ears perked up at the word "pranks," and I looked at him. He grinned. "I'll take that as a yes. So, I was thinking, as we're roomies and we're going to be living together for the best part of seven years, why don't we become pranking buddies, too?" I grinned back.

"Hell yeah! This is going to be amazing!" I leant over to James. "Have you got any ideas?"

* * *

><p>Finally, the last day of the school year swung around. "So, Sirius, when do we get to finally meet your 'baby sister'?" James asked me teasingly. I grinned and swatted at him.<p>

"Eventually, I'm sure. I wouldn't recommend calling her that in front of her, though. She'll probably slap you," I laughed at the look on his face. "Don't pretend to be so scandalised; surely I've told you enough about her that you'd be able to work that out by now." It was true - through the year, we had been learning more and more about each other, and one of the things that the boys never got tired of hearing about was my baby sister. I would constantly regale them with tales of things that we'd gotten up to at home, and, when I received letters from her, we would all sit around the common room fire, and read them together.

The other side of that was true, as well. We wrote back and forth very often, and while she told me storied of what was going on in "the outside world", I'd tell her stories of the four of us, the Marauders, and the latest prank that we'd pulled, or what the teachers were like, or what Snivellus had done that week. Slowly, the other boys began to write to her as well - it started with James stealing my parchment and adding bits on to the end, then progressed to Remus sending full letters to her, when she expressed an interest in being able to talk to them without it having to go through me first.

Reading that had made me laugh, and of course that then meant I had to explain to my room mates about how she'd found out that I was censoring messages that she was receiving when we were younger, and how she'd blown up at me when she caught me out. That story kept them entertained for weeks, and they teased her about it when they wrote letters back to her. She sent letters back berating me for telling them, and berating them for laughing about it, as it had been a "very serious matter" and I "should be ashamed" of myself, both for doing it and for telling them.

I smiled to myself. Soon, we would be back at King's Cross Station, and I would be able to see her again. I couldn't wait.


	2. A Letter? For me?

**_LILY'S POV_**

"Leeeeellllllleeeeeee!"

I sat up abruptly, hitting my head on the low ceiling in my room. I slumped back down onto my bed, hand on my head, where I'd just whacked it. "Oowwwww," I moaned quietly. I heard a snicker next to me, and rolled over quickly. "Oh, it's _you_." I said snappily, and he grinned at me. 'Don't _smile_ at me, Sirius Orion Black! My _head hurts_, and it's _all your fault_!" I couldn't help grinning back, though. That's just how it was in our household. He woke me up, I complained, we shared a smile in much the same way as sharing a secret, and we went to find breakfast. I flicked my gaze to the alarm clock, and my eyes widened dramatically. "What the Hell, Si? It's not even eight yet!" His grin just got bigger.

"Guess what, Lil!" I eyed him suspiciously.

"You've been banned from another bar? You've fallen in love? You've... Blown up something again? You've decided that another neighbour was too loud, so you started blaring your music stupidly loudly again?" He shook his head to each of my suggestions. I rolled back over to face the ceiling. "I dunno, then. It must be earth-shattering for you to be getting me up this early, _especially_ in the middle of the summer holidays!" I paused as a stray thought crossed my mind, and I sat up again, this time avoiding the ceiling, swung myself out of the high bed, and landed lightly on the floor. I looked at him again, then circled him, looking him over. He smirked and stayed still. It was another game that we'd played many times.

Eventually, I was in front of him again, and he collapsed into the chair behind him. "Do I _finally_ get to meet these friends of yours that you've been going on about for the past year?" I asked excitedly. He shook his head, chuckling.

"Not in the way that you're thinking, Hon." I eyed him critically again. The only way I could meet them was if they came over to our house... Wasn't it? He laughed again at my confused expression, then grabbed my hand. "Come on, let's go and have breakfast. I'll explain at some point."

* * *

><p>When we finally reached the stupendously huge kitchen, I stopped in the doorway, and stared. On top of the table was a huge snowy owl. In its beak was a letter. I turned slowly to face my brother, who was fidgeting excitedly.<p>

"Sirius...?" I asked, barely able to comprehend what I was seeing. He shook his head.

"Not a prank, I swear." I looked back at the bird, then, after Sirius gave me a little shove, took a step towards it. It turned to look at me, and I stared back resolutely. It took a step towards me, and I did the same, the I reached out to grab the letter from its mouth. I reached for it rather aggressively, but when I grabbed the letter, I pulled it gently. To my surprise, the owl opened her beak for me to pull it out, then took off.

My eyes scanned the front of the envelope anxiously. If it were for Sirius after all that... But it wasn't. It was for me. I jumped around the kitchen, hugging Sirius when I got back to the door. He grinned and spun me around in circles, careful to avoid hitting the door frame.

"Do you think I should write to the guys?" I asked him, eyes twinkling mischievously. He looked me up and down for a second, then grinned back cheekily.

"Let's leave it as a surprise, hey?" He said, and I laughed and hugged him again, because oh my GOSH I was going to Hogwarts, and it was going to be amazing, with my brother and his friends and the new people I would meet, and the magic that I would learn...

I was so wrapped up in my happy thoughts that I didn't hear Sirius start to speak again. "What?" I blinked up at him. He laughed.

"I said, seeing as they've never met you, and they've never seen a picture, either - shall we see how long it takes for them to work out who you are? You've seen more than enough pictures - you should be able to work out who they are fast enough." I grinned back. This was going to be fun.

Then, I glanced back at the letter - and burst out laughing. "Oh! Si, look, they've addressed the letter to a "Miss Lillian Evans", which means that there's no way they're going to get it from my name," I said, still laughing. Sirius beamed.

"Well, Remus might, but I'm sure he won't say anything to the others - he's smart, that one."

"Actually, Si, I think they'll all work it out faster than you think they will. After all, you're you, and they're boys, and I'm new... It's almost impossible that they won't check me out, which means, if you want this to work, you can't hit them or say anything if they do start looking at me like that." He looked wounded for a second, and I grinned at him. "It's okay, you can hit them once they've worked it out," I said, and he smirked, cracking his knuckles.

"However, another thing is that we won't be able to ride the train together, unless they work it out really quickly, and I won't be able t sit with y'all until they do - oh! Unless I somehow manage to become friends with you, or Remus, I suppose..." I continued rambling, working out what we could do in other scenarios as we walked to the lounge, where we wrote down our plans, then moved on from our prank, and began to discuss everything under the sun.

* * *

><p>For once in my life, I had woken and risen before Sirius - not that I was surprised, of course. It was my first day at a massive new school, where I would have no friends, no way of escaping people, not even Si there to keep an eye on me, especially not if we wanted this prank to work, so I allowed myself the little cluster of nerves roiling in my stomach.<p>

Glancing at the clock on the wall, I noticed that it was nearly time to leave, so I snuck up the stairs to wake Sirius - see how he liked the rude awakenings that he often gave me.

When I reached his room, however, I heard a voice. No, make that two, or maybe even three. My eyes narrowed. How on Earth did he manage to not only sneak them past the wards and our mother, but me, as well. I knew that I am not omnipresent or omnipotent, but still.

I crept silently towards his door, close enough to hear the voices. There were definitely four, and one was definitely Sirius, but I couldn't place the other three. Maybe it was the other Marauders...? But surely Si would have told me - what would happen to the prank if they caught sight of me? I stopped worrying for a minute to listen in to their conversation.

"...Mirrors would work!" Sirius said. My mind went in to overdrive - what mirrors? Work for what? Then I was interrupted by another voice.

"Yeah, yeah, Sirius, we know, just shut up about it already." It had a smooth, melodic quality to it, and I stored it away for further examination later. Everyone laughed, including my brother, and I turned away from the door while I had the chance. Unfortunately, my foot caught something on the floor, and I tripped slightly, muttering an expletive under my breath. The laughter stopped abruptly.

"Did you hear that?" A new voice asked, and everyone fell silent. "I think it came from your end, Sirius." Sirius swore.

"Okay, right, I know who it is then, don't worry about it. I'll just go and grab her, make sure she doesn't tell mum - I'll be back in a minute, okay?" He didn't wait for an answer, and the door opened before I had the chance to fully right myself, and turn around. He was grinning when I did. "Hello, little sister! How're you on this fine morning?" He asked cheerfully, then mouthed "sound upset" to me. Used to acting, thanks to growing up in a household of nutjobs, I instantly went into "angry Lily" mode.

"Oh, I'm just amazing, how are you this morning, Sirius?" I spat, trying desperately to keep from laughing at the faces he was pulling.

"Awesome!" He said, loud enough to be heard through the door. He caught my eye and winked, and I nodded to show that I had understood what he was trying to do. "Look, Lils, can you not say anything about this to Mum? She'd kill me if she found out that I'd nicked 'em." I sighed dramatically.

"Fine, whatever, you do what you want. It's not like anything I can say will stop you," I said scathingly, stomping my feet as I pretended to walk away, getting quieter and quieter. Eventually, I stopped, and gestured into the room. Si nodded and gave me a thumbs-up. Obviously he'd wanted me to do that - why, I have no idea.

I waited outside his door for a few moments, but when I didn't hear anything, I sighed and went back down to the kitchen to see what there was to eat.


End file.
